JPH1130722A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the high-performance hybrid optical integrated module used for optical communication. SOLUTION: The optical module includes an active optical element 2 which has a light input end and a light output end at opposite positions on the substrate and a passive optical circuit having an input optical connection part 11, an active optical element input connection part 12, an active optical element output connection part 13, and an output optical connection part 14 and further has the active optical element input connection part 13 of the passive optical circuit and the light input end of the active optical element 2 coupled optically and the active optical element output connection part 13 of the passive optical circuit and the optical output end of the active optical element 2 coupled optically; and the active optical element input connection part 12 and active optical element output connection part 13 are so arranged that the optical axis of the input light from the input optical connection part 11 is not parallel to the optical axis of the output light from the output optical connection part 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-performance hybrid optical integrated module used for optical communication.

[0002]

2. Description of the Related Art In recent years, quartz optical waveguide circuits (PLCs: Planar Lightwave Cir
interest in hybrid optical integrated technology that combines passive optical circuits such as cuit) and active optical devices such as semiconductor optical devices. Until now, a quartz PLC and a semiconductor laser (L
Optical transmission / reception modules combining D) and a photodetector (PD) have been developed. In addition, if a hybrid integrated circuit using optical input / output type active optical elements such as optical amplifiers and optical modulators is realized,
Its scope of application is further expanded.

FIG. 8 is a configuration diagram of a hybrid integrated type 4 × 4 optical switch configured by mounting a semiconductor optical amplifier (SOA: Semiconductor Optical Amplifire) on a quartz PLC [Y. Yamada et. J. Lightwave Technol. Vo
l. 10, pp. 383-390, 1992]. In FIG. 8, reference numeral 1 denotes a quartz PLC substrate, 10 denotes an optical waveguide, 11 denotes an input optical connection, 12 denotes an active optical element input connection, 13 denotes an active optical element output connection, and 14 denotes an output optical connection. , 30 indicate an input optical fiber and 40 indicates an output optical fiber. Also,
Reference numeral 2 denotes an active optical element, in which an SOA is mounted in this example.

In the optical module of FIG. 8, the optical axis of the SOA is arranged in parallel with the optical axis of the input light from the input optical fiber connection section 11 on the silica PLC. The optical axis of the output light at the output light connection unit 14 is also parallel to each of the above optical axes.

[0005]

In a hybrid optical module equipped with active optical elements of both ends coupling type as shown in FIG. 8, if the optical axes of the respective optical coupling portions are arranged in parallel, the following problems occur. . That is, the light that is not coupled to the optical waveguide 10 at the input optical connection portion 11 and the light that is not coupled to the active device at the active optical device input connection portion 12 are both leaked light and pass through the quartz PLC substrate. Part of the light is input to the output optical fiber connected to the output optical connection unit 14. If such a situation occurs in the optical switch shown in FIG. 8, a weak optical signal propagates through the optical switch even if the optical signal is originally in an OFF state in which the optical signal should be cut off. As a result, the extinction ratio deteriorates. Occurs.

In the case where an optical modulator is used as an optical element of both ends coupling type, if the leaked light is coupled to the output optical fiber again, there is a problem that the amplitude of the output modulation signal becomes small.

[0007]

In order to solve the above-mentioned problems, it is important to adopt a structure in which light leaking from the passive optical circuit board is not coupled to the output optical fiber again.
As described above, the main locations where leakage light is generated are the input optical connection and the active element input connection. Therefore, in the present invention, the optical axes of the respective components are arranged so as to be inclined so that the leaked light generated in these places is not coupled to the propagation path of the signal light. That is, according to claim 1 of the present invention, in the optical module of the present invention, an active optical element having an optical input end and an optical output end at opposing positions on a substrate, an input optical connection section, and an active optical element input connection. , An active optical element output connection, and a passive optical circuit having an output optical connection, wherein the active optical element input connection of the passive optical circuit and the optical input end of the active optical element are optically coupled, In an optical module comprising an active optical element output connection part of the passive optical circuit and an optical output end of the active optical element, the active optical element input connection part and the active optical element output connection part of the passive optical circuit are provided. The active optical element input connector and the active optical element output are connected so that the optical axis of the active optical element does not become parallel to the optical axis of the input light from the input optical fiber connector and the optical axis of the output light from the output optical fiber connector. A connection part is arranged.

According to a second aspect of the present invention, at this time, the optical axes at the active optical element input connection section and the active optical element output connection section of the passive optical circuit correspond to the input light from the input optical connection section. The active optical element input connection and the active optical element output connection may be arranged so as to be orthogonal to the optical axis and the optical axis of the output light from the output optical connection.

[0009]

FIG. 1 is a structural view of an optical module for explaining an embodiment of the present invention, in which an active optical element 2 is mounted on a quartz-based PLC substrate 1. The active optical element 2 is optically coupled with the quartz-based waveguide 10 at the active optical element input connection section 12 and the active optical element output connection section 13 with their optical axes aligned with each other. Then, the input optical fiber 30
The entire optical module including the optical fiber 40 and the output optical fiber 40 constitutes an optical module.

Here, the optical axis PQ of the input connection section 12 and the output connection section 13 of the active optical element 2, the optical axis MN of the input optical connection section 11 and the optical axis RS of the output optical connection section 14 are not parallel. Are arranged to have an angle θ. For this reason, even if a part of the leaked light from the active optical element 2 reaches the output optical fiber connection portion 14, the leaked light is caused by an angular deviation between the leaked light propagation axis and the optical axis of the output optical fiber 40. The amount that the component couples to the output optical fiber 40 is significantly reduced.
At the same time, the input optical connection section 11 and the output optical connection section 14 are arranged so as not to face each other directly, so that the input optical connection section 11 is generated at the input optical connection section 11 due to a displacement between the propagation axis of the leaked light and the optical axis of the output fiber 40. The amount of light coupling into the output optical fiber 40 is also significantly reduced. As a result, a high-performance optical module can be realized.

As described above, if the optical axes of the input light and the output light of the active optical element and the optical axes of the input optical connection portion and the output optical connection portion are arranged not parallel but at an angle, for example, Even if a part of the light leaked from the optical element reaches the output optical fiber connection portion, this light component does not couple with the light propagated through the output optical fiber. As a result, a high-performance hybrid optical module can be realized.

Further, when the optical axis of the active optical element and the optical axis of the optical fiber connection portion are arranged at an angle, the two effects are further enhanced by arranging the two at right angles. In addition, this arrangement also has an effect of facilitating a mounting process for mounting the active optical element on the passive optical circuit board.
Generally, to mount an active optical element on a passive optical circuit board, it is necessary to use the active optical element in an optical element mounting device. This type of device is based on a two-axis fine movement of XY (vertical-horizontal).
If the above-mentioned orthogonal arrangement of the active optical elements having a slight angle correcting mechanism is adopted, it becomes possible to mount the elements only by the basic operation of the mounting apparatus, and the mounting alignment speed is improved. is there.

[0013]

【Example】

[Embodiment 1] FIG. 2 shows a configuration diagram of a hybrid optical module according to an embodiment of the present invention. 1 is a quartz PLC substrate, and 10 is a quartz optical waveguide on the substrate. 11 is an input optical connection, 12 is an active optical element input connection, 13 is an active optical element output connection, and 14 is an output optical connection. Reference numeral 2 denotes an active optical element mounted on the quartz-based PLC substrate 1. In this embodiment, a four-channel semiconductor optical amplifier (S
OA). 30 is an input optical fiber,
40 is an output optical fiber. This module as a whole constitutes a four-channel optical amplifier module. The structural features of this module include an optical axis MN at the input optical connection 11 and an optical axis RS at the output optical connection 14.
Are arranged so as to be substantially orthogonal to the optical axis PQ at the active optical element input connection section 12 and the output connection section 13.

With such a configuration, as shown in FIG. 2, leaked light generated at the input optical fiber connection portion propagates to the region A on the substrate facing the input optical connection portion 11. Therefore, this leaked light component does not reach the SOA, which is the active optical element 2 mounted on the substrate. Further, the leakage light generated at the active optical element input connection section 12 and the active optical element output connection section 13 propagates to the region B on the substrate. Therefore, the leak light component does not reach the output light connection unit 14. Therefore, by employing this configuration, it is possible to significantly reduce the leak light component coupled to the output optical fiber 40.

This effect is remarkably exhibited when the optical amplifier module shown in FIG. 2 is used as an optical gate switch.
That is, the optical amplifier transmits / amplifies the optical signal when current is injected, but absorbs and blocks the optical signal when no current is injected. Therefore, it can be used as an optical switch by utilizing this property. The important characteristics from the standpoint of such an optical switch are the light output intensity when the current is injected and the switch is turned on, and the OFF when the current is not injected.
The ratio of the light output intensity of the state, that is, the extinction ratio. When leakage light is present, a small amount of light is transmitted even in the OFF state, so that the extinction ratio deteriorates.

When the optical switch characteristics of the optical module shown in FIG. 2 were evaluated, the module gain in the ON state was 10d.
B, while the gain in the OFF state is −35 dB (ie,
35 dB), and an extinction ratio of 45 dB was obtained. For comparison, a module having a conventional parallel arrangement shown in FIG. 3 in which the optical axes at the respective connection portions of the optical module were arranged in parallel was manufactured, and the same characteristics were evaluated. Was 10 dB, the gain in the ON state was -25 dB, and the extinction ratio was 35 dB.

[Embodiment 2] FIG. 4 is a configuration diagram of an optical module according to a second embodiment of the present invention. In this module, an SOA is mounted as an active element 2 on a quartz PLC substrate 1 as in the first embodiment. Input optical connection 1
1. The point that the optical axis of the output optical connection section 14 is arranged so as to be substantially orthogonal to the active optical element input connection section 12 and the output connection section 13 is common to the first embodiment. This embodiment is different from the first embodiment in that the output optical connection unit 14 is provided on the same end face as the input optical connection unit 11 on the substrate. This way,
Since the propagation direction of the input light to the optical module is different from the propagation direction of the output light from the module by 180 °, the effect of blocking the leak light is further enhanced.

Embodiment 3 FIG. 5 is a structural view of an optical module according to a third embodiment of the present invention. Reference numeral 1 denotes a quartz-based PLC substrate on which two arrayed waveguide grating circuits (Arrayed w
aveguide grating (AWG) 50-
1, 50-2 are formed, during which the active optical element 2
SOA arrays are hybrid-integrated. In this embodiment, the configuration of the PLC is more complicated than in the first and second embodiments. However, even if the configuration of the PLC becomes complicated, the main location of leakage light in the hybrid optical integrated circuit is an optical coupling portion between different types of optical elements, that is, an input optical connection section 11, an active optical element input connection section 12, an active optical element input connection section 12, and an active optical element input connection section 12. An optical element output connection section 13 and an output optical connection section 14. Therefore, by arranging the connection parts so that the optical axes are non-parallel, the influence of light leakage can be suppressed. Therefore, also in this embodiment, the optical axis of the input optical connection section 11 and the optical axis of the output optical connection section 14 are arranged so as to be substantially orthogonal to the optical axes of the input connection section and the output connection section of the active optical element. is there.

This optical module functions as a variable frequency filter for transmitting an arbitrary wavelength from among four signal lights having different wavelengths input from the input optical fiber. That is, the wavelength-multiplexed signal light is transmitted to the first stage AWG.
After being separated and guided to four optical waveguides for each wavelength at 50-1, current is caused to flow to the SOA arranged in each waveguide through which the demultiplexed wavelength passes, thereby turning the SOA ON. After extracting only the desired wavelength, the AWG 50-2 at the subsequent stage combines it into one optical waveguide and propagates it to the output fiber 40. At this time, if the leakage light is large, the signal of the wavelength that is originally desired to be blocked cannot be completely blocked. However, since the configuration of the present invention can prevent light leakage, excellent filter characteristics can be exhibited.

The optical module function is such that all the functions are integrated on a single PLC substrate as shown in FIG. 5, and as shown in FIG.
The PLC which is separated into three parts, the SOA module part 60-2 and the second AWG part 60-3, and manufactured on another substrate may be finally connected directly. In this case, SO
If the module having the structure shown in the first embodiment is adopted as the A module unit 60-2, an optical module having excellent filter characteristics without the influence of leak light can be realized.

[Embodiment 4] FIG. 7 is a structural view of an optical module according to a fourth embodiment of the present invention. In this embodiment, two types of active optical elements 2 and active optical elements 21 are mounted on a passive optical circuit board 1 in series. One active optical element 2 is an optical modulator, and is an optical input / output double-ended optical element. The other active optical element 21 is an LD
An array, which is a single-ended optical device. The passive optical circuit includes an input optical connector 11, an active optical device input connector 12, an active optical device output connector 13, and an output optical connector 14.
Having. This optical module is an optical module that externally modulates the output light of the LD array 21 with the modulator 2.
If the leak light from the output light from the LD array 21 leaks into the output optical fiber 40, the amplitude of the modulation signal from the optical module becomes smaller. Therefore, in order to improve the performance, the leak light is coupled to the output optical fiber. It is important not to let them.

In this embodiment, the optical axes of the input optical connection section 11 and the output optical connection section 14, the active optical element input connection section 12 and the active optical element output The optical axes of the connecting portions 13 are arranged so as to be orthogonal to each other, and the positions of the input optical connecting portion 11 and the output optical connecting portion 14 are positioned so as not to directly face each other. These arrangements prevent leakage light from coupling into the output optical fiber.

[Embodiment 5] FIG. 8 shows the optical module function of the embodiment 4 implemented in a slightly different arrangement. The components are exactly the same as in the fourth embodiment. This embodiment is different from the fourth embodiment in that the optical axes of the input optical connection section 11 and the output optical connection section 14 and the optical axes of the active optical element input connection section 12 and the active optical element output connection section 13 are parallel to each other. Although they are set at an angle of approximately 45 ° so as not to be orthogonal, they are not orthogonal. Although they are not orthogonal, the inclination angle 45 ° between the optical axes is set to be larger than the far field diameter of the LD output light and the far field diameter of the optical modulator 2, so that the effect of preventing leaked light is sufficient. high. With such an arrangement, the size of the substrate can be reduced as compared with the module of FIG. 7 which is an orthogonal arrangement.
This is an advantage of the arrangement.

On the other hand, the arrangement of this embodiment in which the LD and the optical modulator are not parallel or orthogonal is disadvantageous in that when the active optical element is mounted on the passive optical rotating board, the mounting process takes a little time. is there. That is, in the optical element mounting machine, generally, the XY (vertical-horizontal) drive is generally used for the fine movement unit having the alignment function. Regarding the angle adjustment, in order to correct the slight deviation from the X direction and the Y direction,
In many cases, the movable range of the rotating shaft is limited to 10 ° or less. For this reason, when an optical element mounted with the XY axis aligned with the optical axis direction and an element mounted at an angle of about 45 ° from the XY axis coexist as in this embodiment, the LD After mounting the substrate, the operator must manually rotate the substrate in accordance with the optical modulator.

As a result, the labor in the optical element mounting process increases. On the other hand, in FIG. 5, although the optical axis of the LD and the optical axis of the optical modulator are orthogonal to each other, they are both parallel to either the X axis or the Y axis.
There is no need to rotate the board after mounting. Therefore, which of FIG. 7 and FIG. 8 should be adopted should be determined in consideration of the permissible substrate size and mounting work load.

[0026]

As described above, as described through the embodiments,
According to the present invention, in a hybrid optical integrated module equipped with a double-ended active optical element, the optical axis of the double-ended active optical element and the optical axes of the input connection end and the output connection end of the passive optical circuit, Since they are set in the parallel state, it is possible to prevent the leakage light generated at each connection point on the passive optical circuit from being coupled to the output optical fiber. As a result, a high-performance optical module can be realized.

In particular, when the two optical axes are arranged so as to be substantially orthogonal to each other, there is an advantage that the effect of preventing leakage light is improved and the mounting process of the optical element is simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical module according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical module according to a first embodiment of the present invention.

FIG. 3 is a configuration example (comparative example) of an optical module arranged in parallel with the optical axis.

FIG. 4 is a configuration diagram of an optical module according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of an optical module according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing another type of the module according to the third embodiment.

FIG. 7 is a configuration diagram of an optical module according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of an optical module according to a fifth embodiment of the present invention.

FIG. 9 is a configuration example of a conventional double-ended hybrid optical module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Passive optical circuit board 2 Active optical element 10 Passive optical waveguide 11 Input optical connection part 12 Active optical element input connection part 13 Active optical element output connection part 14 Output optical connection part 21 Active optical element 30 Input optical fiber 40 Output optical fiber 50 -1, 50-2 Array waveguide grating circuit 60-1 First AWG unit 60-2 SOA module unit 60-3 Second AWG unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Himeno Nippon Telegraph and Telephone Corporation 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo

Claims (2)

[Claims] 1. An active optical element having an optical input end and an optical output end at opposing positions on a substrate, an input optical connection, an active optical element input connection, an active optical element output connection, and an output connection. A passive optical circuit having an active optical element input connection part of the passive optical circuit and an optical input end of the active optical element, and an active optical element output connection part of the passive optical circuit and the active light element. In an optical module configured by optically coupling an optical output end of an element, an optical axis at an active optical element input connection part and an active optical element output connection part of the passive optical circuit has an input light from the input optical connection part. An optical module, wherein an active optical element input connection section and an active optical element output connection section are arranged so as not to be parallel to the optical axis of (1) and the optical axis of output light from the output optical connection section. 2. An optical axis at an active optical element input connection and an active optical element output connection of the passive optical circuit, wherein an optical axis of the input light from the input optical connection and an output light from the output optical connection. 2. The optical module according to claim 1, wherein an active optical element input connection part and an active optical element output connection part are arranged so as to be orthogonal to the optical axis.